In a device and method for controlling packet flow, priority data of a packet received by one of a plurality of ports are determined. A packet memory is monitored to determine whether an address pointer of the packet memory exceeds a predetermined limit value. A port is selected to control packet flow by using the priority data when the address pointer of the packet memory exceeds the predetermined limit value. Then, the selected port is directed to control the packet flow. By using the priority data designated to a packet or a port, the packet flow may be controlled in consideration of various kinds of network services.